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Question & Answer
Classification: FAQ_CLASSIFICATION
Date: FAQ_DATE
What is the polarity of the XS40 Board serial EEPROM?
Q:
I am using a Ver. 1.0 XS40 Board. For connecting 'INIT low' line from the FPGA to line 3 of the eeprom, the polarity of line 3 should be 'RST low / OE high'. But on the XS40 schematic, it shows line 3 as 'RST high / OE low'. So is the schematic a typo and really supposed to be 'RST low / OE high'?
A:
The XC4000 pulses its /init line low at the beginning of its configuration sequence. This resets the serial eeprom to the start of its bitstream. So the serial eeprom is reset=0, oe=1. This is the default configuration for the AT17C*** series.